The present invention relates to a temperature compensating composition for ceramic dielectrics which has a high breakdown voltage and prolonged life.
Conventionally, as a temperature compensating composition for ceramic dielectrics, there has been publicly known a La.sub.2 O.sub.3 -TiO.sub.2 -CaO-MgO based composite which comprises 3.0-25.0 mol % La.sub.2 O.sub.3, 51.0-62.0 mol % TiO.sub.2, 0.5-45.0 mol % CaO and 1.0-45.0 mol % MgO at the conversion of oxides of lanthanum, titaium, calcium and magnesium to respectively La.sub.2 O.sub.3, TiO.sub.2, CaO and MgO. However, the grain size thereof is more than 5 .mu.m, consequently it is unsuitable for a raw material of such a product as a layer-built capacitor which is used in a high electric field. Namely, in the case where the grain size is large, an electric field strength falling on one grain thereof becomes larger and consequently a breakdown voltage becomes lower and a life becomes shorter, resulting in a lowering of reliability. Further, as it contains La.sub.2 O.sub.3, use of alumina setter is required. Therefore, use properly of the alunina setter and zirconia setter which is used in an usual composition for ceramic dielectrics is required, thereby making the manufacturing process more complex. The present invention has been devised by overcoming the above mentioned defects of the conventional compositions.